"We could hear them laughing at us from above, when we tried to shoot at them," said Wayne Stanton, a US serviceman. The moment a plane or helicopter approached "they would stop firing and just run into their bunkers and hide in their caves".

US Army Specialist Stanton was only wounded in the fighting, and ferried from the mountains of Shahikot in eastern Afghanistan to Germany, where he is being treated at an American military hospital. Eight of his colleagues were less fortunate, losing their lives in Operation Anaconda, the first extended ground battle of the five-month old campaign.

No one knows how long the fighting, in which at least 15 allied troops have been killed and 55 wounded, will last. But it is becoming clear that bombing, superior equipment and the commitment of special forces on the ground are giving the US and its partners the upper hand.

The noose yesterday tightened further as 1,000 or more troops loyal to the interim government of Hamid Karzai moved to Gardez. The US-led forces on the front line may also be joined by British commandos, trained for mountain fighting. Yesterday the Ministry of Defence described as "speculative" reports that 200 Royal Marines on standby aboard HMS Ocean in the Arabian Sea were about to move into the Shahikot battle. Another 400 troops are believe to be on standby in the UK.

But snow storms and thick cloud cover at the end of last week slowed the momentum of the allied assault, forcing the US Defense Secretary, Donald Rumsfeld, to revise his estimate that the eight-day battle would be over this weekend.

Yesterday, the weather relented and the bombers and strike aircraft resumed their bombardment.

After the initial bloody setbacks, US commanders now claim they have cleared al-Qa'ida and Taliban fighters from many high positions from which they had dictated the pattern of the ground battle in its early stages. Supply lines have been cut, they say and the flow of new fighters to the mountain redoubts has slowed to a trickle.

"We're killing these guys in bucket loads," one US official said. The Pentagon estimates Taliban and al-Qa'ida dead at up to 700. But despite the casualties there were no reports of surrender. As the bombing restarted, Afghan officials issued a new 48-hour deadline for resisters to give up their arms – but the expectation is that this will be a fight to the finish.

As Specialist Stanton discovered, the enemy is using every advantage offered by familiar but enormously difficult terrain: "We were fighting in their backyard, they know every crevice, every cubby-hole, every cave."

No one knows how many are left. According to some estimates, up to 4,000 guerrillas could be holed up in Shahikot and the surrounding region, under the Taliban commander Saeef Rahman Mansour. Other pockets may exist nearby. Having been surprised by the feeble resistance early on, US analysts are still puzzled as to why it is continuing so ferociously. Some speculate that top

al-Qa'ida or Taliban figures – possibly even Osama bin Laden – may be cornered there, but intelligence has been unable to confirm this.

Last night, the involvement of British troops remained uncertain. An MoD spokesman admitted that commandos were aboard HMS Ocean, but would only say that they could be used "for a range of operations if there was a requirement". Nor would he confirm that the US had requested British assistance: "We and the Americans are talking all the time."